A FATHER found guilty of murdering his six-month-old son and attempting to murder another son won permission to challenge his convictions at the Court of Appeal.

The man, who cannot be named, was, in part, convicted on evidence given by Professor Sir Roy Meadow, an expert in the field of sudden infant deaths.

The reliability of Professor Meadow's evidence has been called into question following a number of high profile cases involving mothers who were alleged to have killed their babies.

The man, from Caldicot, was convicted in December 2002 at Cardiff crown court, and sentenced to life imprisonment. He has always maintained his innocence, and says he was a loving father.

No date was set for his full appeal, which will last two days. Barrister Alistair Webster QC yesterday told three judges at London's Court of Appeal that new statistical evidence could undermine that given by Professor Sir Roy Meadow at the man's Cardiff crown court trial.

And the judges, led by Lord Justice Scott Baker, agreed there were "arguable grounds" that the convictions were "unsafe".

The fresh evidence will come from Professor Ray Hill, a statistician, and will attack Sir Roy's studies into the odds against sudden infant death syndrome.

"We don't wish to raise the father's hopes," said Lord Justice Baker, who was sitting with Mr Justice Forbes and Judge Jeremy Roberts QC.

"There was a formidable case against him, but in the current climate of uncertainty about the cause of sudden infant death in very young children we think the issues raised by Professor Hill and their possible relevance should be fully explored."

Mr Webster also won permission to cite new evidence of sudden infant deaths in the father's wider family.

The father was found guilty of murdering one son in 1998 by smothering him and trying to murder a second, younger, son in the same way in 1999. At trial, the crown court heard he was only stopped because a nurse spotted him when the boy was in hospital.

The barrister will also challenge trial judge Mr Justice Christopher Pitchford's decision to allow evidence to be heard of the father's "macabre" fascination with his dead son.

Mr Webster had argued that by allowing the evidence, the judge had effectively gone against an earlier ruling he had given preventing Munchhausen's by Proxy being discussed at the